The present invention relates to a transportation hanger having vertical movement in overhead systems.
In certain technological processes typical of automobile manufacturing and provided with continuous overhead transportation systems it is necessary to change the height of the objects handled in relation to a predetermined working level for reasons of accessibility and to enable operators or automated working means to respect ergonomics or machine optimization.
For example, there may transit on the same transportation line a basic vehicle type or so-called derivative types which could require different and changeable working heights. In addition, different vehicles might transit simultaneously on the same line or the lines might have to be converted for processing of different models.
Lastly, for better ergonomics in the manual work stations the ability to change the height above the floor of vehicles being processed must be provided so as to adapt it to the operators"" height.
In the prior art, transportation hangers equipped with a powered vertically movable frame for moving the object transported to a desired height above the floor upon command have been proposed.
A first problem in the design of hangers with onboard lifting is due to the fact that such a transportation system must naturally allow the longest desired travel without noticeably increasing the space occupied by the closed frame hanger in relation to the space occupied by a fixed frame hanger because the structure of the entire transportation system is conditioned by building height, clear spans, crossover constraints, and overpassing of fixed parts or other systems.
Other design problems arise from the fact that the hangers must have sufficient rigidity against thrusts against the frame and in particular when it is completely lowered and in case of failure it must ensure holding of the movable frame around or beneath which people work.
The prior art has proposed hangers equipped with a powered parallelogram board which however are suited to medium width runways. For higher runways hangers with frames having complicated and cumbersome parallelograms or cable systems accompanied by a stiffening system have been proposed.
For example, there have been proposed transportation hangers having cable lifting and equipped with stiffeners articulated on the X and Y axes. These stiffeners are normally three in number and articulated in such a manner as to accompany the movable frame in its travel.
Each stiffening is provided by two rigid members connected together by a hinge. Basically they belong to a single type; the rigid members are prismatic rods similar to boards hinged at the center of junction and at the two ends. These stiffening members are installed on the hanger in such a manner as to provide stiffening in the plane perpendicular to the plane of oscillation. Thus torque links one of which folds back transversally and two longitudinally to the hanger extension are obtained. The stiffness of the structure is however not always satisfactory. In addition, in these structures the arrangement of the hinges and in particular the use of three hinges for each torque link require a high degree of alignment accuracy.
The general purpose of the present invention is to remedy the above mentioned shortcomings by making available a structure easy to produce and having satisfactory stiffness and safety.
In view of this purpose it was sought to provide in accordance with the present invention a hanger for transportation of objects along a suspended runway comprising an upper part constrained to run along the runway and a lower part for load support connected to the upper part through a raising and lowering system with there being arranged between the two parts a stiffening structure against oscillations characterized in that the stiffening structure comprises three stiffening members one of which is a parallelogram and is arranged on the median plane of the hanger while the other two are made with oscillating rods and are positioned with one on each side of the central one.